1. Field of the Invention
The present invention relates to a protection device for a storage unit (a refill unit) of ink cartridges utilized in an ink jet printer.
2. Description of the Related Art
An ink jet printer known in general has a housing in which a print head, one or more ink tanks (ink cartridges), and a carriage is installed. The print head includes a nozzle for discharging ink, and is arranged on the carriage. The carriage is able to move in the perpendicular direction with respect to a printing medium (a sheet of printing paper, for example); that is, the carriage is able to move in the main scanning direction. The print head is connected to the ink tank, and discharges the ink provided therefrom via the nozzle. The printing medium is conveyed through the housing of the ink jet printer, and the ink discharged from the nozzle is printed thereon.
The ink jet printers can be roughly categorized into two types: an on-carriage type, and an off-carriage type. Such categorization can be made based on the arrangement of the ink cartridge. The on-carriage type and the off-carriage type both include a storage unit, or a storage case for detachably storing the ink cartridge. The on-carriage type has the storage unit arranged on the movable carriage. With this type of carriage, the ink is provided directly from the storage unit to the print head. On the other hand, the off-carriage type has the storage unit arranged inside the housing, but not on the movable carriage. The ink cartridge stored in the storage unit is connected to the print head by a relaying member; for example, an ink tube. The ink is provided from the remote storage unit to the print head that is supported on the carriage via the ink tube.
With either of the types of ink jet printers as described above, the ink cartridge must be replaced with a new one, or be refilled, when the volume of remaining ink becomes insufficient.
With the typical types of ink jet printers as described above, the storage unit has an ink inducing member that provides ink to the print head. Correspondingly, the ink cartridge has a connecting portion, such as an ink providing valve. To provide the ink to the print head from the ink cartridge, the ink inducing member of the storage unit is connected to the connecting portion of the ink cartridge. In a case where the ink inducing member is in the shape of a narrow needle or tube, the ink inducing member is easily bent or broken in the course of installing and removing the ink cartridge to and from the storage unit. Thus, a guiding portion, for example, a plurality of guiding ribs or a guiding tube section are formed on the periphery of the ink inducing member, while an insert tube corresponding to the aforementioned guiding ribs or the guiding tube section is formed on the connecting portion of the ink cartridge, to insert therein.
Inkjet printers of both the on-carriage type and the off-carriage type undergo a print test before shipment. The print test is performed to confirm that the printing mechanism is functioning. In such a test, one or more ink cartridge is installed in the storage unit, and after the print test, the ink cartridge is removed from the storage unit before shipment. The ink inside the print head can be left or removed prior to shipment. In the case where the ink is removed from the print head, the print head is refilled with a preservative liquid which has the same characteristic as the ink without pigments or dyestuffs. Then, a protection device, such as a protection cap or a dummy cartridge (that is, a cartridge with no ink inside), is installed in the case to cover the ink inducing member. The protection device prevents the leakage of the ink or the preservative liquid (the term “liquid” will be used as the general term for both the ink and the preservative liquid in the description below). The surface of the print head on which the nozzle is arranged is also covered with a nozzle cap to prevent the leakage of the liquid, and for the protection of the nozzle. Such a technique is taught in the Japanese Patent Application Publications No. 2002-79690, No. 2004-230857, No. 2005-238857, and No. 2003-54000.
Hence, in order to seal the tube or needle shaped ink inducing member, a rubber cork (see FIG. 3 of the Japanese Patent Application Publication No. 2002-79690), or a sealing portion (see Japanese Patent Application Publication No. 2005-238857 and No. 2003-54000) is arranged on the protection device.
In the above-mentioned case of sealing the tube or needle shaped ink inducing member with the protection device, the rubber cork or a rubber cap is arranged on the protection device. However, if the protection device is installed or removed in an improper position or angle, the ink inducing member is bent or broken.
Moreover, in the course of transporting the ink jet printer, the environmental condition of the ink jet printer may change; for example, following impact from vibrations due to transportation, the seal between the protection device and ink inducing member may be loosened, resulting in ink leakage. Or, a change in temperature, and/or change in atmospheric pressure may occur. If air and liquid remain inside the sealed portion, the aforementioned changes cause the volume of the air and liquid to change, resulting in a loosening of the seal and ink leakage. Therefore, the cork ( or the rubber cap) of the protection device must be sealed tightly in order to prevent the occurrence of undesirable conditions described in the above-mentioned cases. For this reason, the cork (that is, the protection device) is tightly inserted into or engaged with the ink inducing member.
In such case, however, excessive force is required in the process of removing the protection device, and if the removal direction is not parallel to the ink inducing member, the ink inducing member is bent or broken.